A manufacturing method of a glass substrate used for semiconductor devices such as image sensors is known as described in JP-A-2006-282480 and as illustrated in FIG. 5.
This publication describes providing grooves 502 on a glass substrate 501 so that the amount of warp in a thin-film attached glass substrate before being cut into individual pieces by methods such as dicing is reduced to substantially the same level as that in a thin-film attached glass substrate obtained when the glass substrate 501 having a thin film 503 is cut at the positions of the grooves 502. In this way, the glass substrate and a semiconductor wafer having a plurality of semiconductor elements can be combined with each other with improved processing accuracy for these elements.